Completing 12 from dual boards

Respected Sir/Mam
I have completed my 12 from NIOS board this year(2018-19). My aim is
to get into IIT and to do so I need to appear for JEE. I had passed 10
and 11 from CBSE board and my TC, Migration Certificate etc are still
registered in CBSE from my previous school from which I passed my 11.
But can I write 12 from CBSE the next year(2019-20) and appear in JEE
in 2021 based on CBSE marks
Thank you